Theoretical Study Of Tunable Terahertz Absorbers And Sensors Based On Metamaterials

Traditional metamaterial absorbers have various shortcomings,such as single function,complex cell structure,weak tunability,and low absorption rate,which are limited in complex electromagnetic environments and can hardly meet people’s needs.In order to achieve high absorption,high bandwidth and tunability of incident electromagnetic waves,a multi-frequency tunable metamaterial sensor and a broadband tunable metamaterial absorber are designed around two materials,graphene and vanadium dioxide,respectively,combined with different periodic patterns,and the main research contents are as follows:First,a multi-band ultrasensitive terahertz sensor based on a tunable graphene metamaterial absorber is proposed.The simulated structures showed that four perfect absorption peaks over 99.9%were excited at frequencies of 4.879 THz,5.800 THz,7.464THz and 8.088 THz.When the angle of incidence is close to 80°,more than 90%absorption can still be obtained.In addition,this terahertz metamaterial absorber can be used as a high-sensitivity refractive index sensor with maximum refractive index sensitivity,quality factor Q,and sensor performance index FOM of 2.458 THz/RIU,230.258,and 73.323 RIU^-1,respectively.Second,a broadband tunable terahertz metamaterial perfect absorber based on vanadium dioxide is proposed.The simulation shows that when the vanadium dioxide is in the metallic state,the absorber has excellent broadband absorption characteristics and an absorption bandwidth of 0.97 THz,with an absorption amplitude of over 90%in the broadband absorption band from 0.73 to 1.70 THz.The conductivity range varies from200S/m to 2×10⁵S/m as the vanadium dioxide changes between the insulating and metallic states,and the absorptance of this broadband absorber is dynamically adjusted from 3.4%to95.5%.In addition,the absorber has wide-angle absorption and polarization insensitivity.Our results can be applied to wave modulation related fields such as biomedical sensing,smart absorbers,terahertz imaging,military radar,electromagnetic stealth,etc.